JPH11192734A - Image forming apparatus and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the start-up for performing the scanning of a printing medium and the section required in this start-up, in an apparatus wherein a plurality of printing means having printing elements are arranged and the scanning of the printing medium is performed in a direction different from the arranging direction, to miniaturize the apparatus and to increase a printing speed. SOLUTION: Means (scales 61 and encoders 62) detecting the respective positions of a plurality of printing means in a scanning direction and a means for independently controlling the driving timings of printing elements with respect to a plurality of the printing means based on the data detected by the detection means are provided. By this constitution, printing operation can be performed even during acceleration and deceleration periods at times of the start and completion of scanning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus and an image forming system for forming (recording) an image on a print medium based on image information, for example, image information obtained by reading a document. ), Magenta (M), yellow (Y), and black (K).

[0002]

2. Description of the Related Art Conventionally, as this type of apparatus, for example, four independent heads for ejecting cyan, magenta, yellow, and black inks are juxtaposed and mounted on one carriage, and the carriage is relatively moved a plurality of times. 2. Related Art There is a color inkjet printer that forms an image by discharging ink on a print medium.

In order to discharge ink to a target position on a print medium, the speed of the carriage moving on the print medium is always kept constant. Therefore, an apparatus is designed to keep the load of the carriage constant. In addition, control for keeping the rotation speed of the motor for moving the carriage constant has been performed. Furthermore, using a method of preparing a scale on which information at equal intervals is formed, reading the scale, generating a pulse signal every time the carriage moves at a constant interval, and controlling the ink ejection timing based on the pulse signal. Some devices were there.

[0004] In any case, a running distance is required to start the carriage from a stop to a target speed and obtain a constant speed, and the moving speed is required until the carriage moves out of the printing range. Is required to be constant, and thereafter, a distance is required to reduce the speed of the carriage and stop.

[0005]

Accordingly, in the image forming apparatus, a predetermined distance is required for starting up and lowering the carriage in addition to the printing range as the moving range of the carriage, which reduces the size of the apparatus. Was a constraint. Further, in addition to the actual printing operation time, it takes time to move between the start-up and shutdown sections, which is a constraint in improving the print throughput.

The present invention relates to an apparatus for forming an image by scanning a plurality of printing means or a member on which the printing means is mounted relative to a print medium. It is an object of the present invention to shorten the required section, thereby reducing the size of the apparatus and improving the printing speed.

[0007]

For this purpose, the present invention provides:
An apparatus for forming an image by using a plurality of printing means having printing elements and scanning relative to a print medium in a direction different from the direction in which the plurality of printing means are arranged, wherein Means for detecting a relative position of each of the plurality of printing means, and means for independently controlling the drive timing of the printing element for each of the plurality of printing means based on the detected information. It is characterized by having.

The detecting means includes a scale extending in the scanning direction and having information formed at a predetermined interval, and an encoder which is relatively scanned together with the printing means and detects formation information on the scale. A plurality of sets of the scale and the encoder corresponding to the plurality of printing means.

Alternatively, the detection means may be a single scale extending in the scanning direction and having information formed at predetermined intervals, and an encoder which is relatively scanned with the printing means and detects formation information on the scale. And a plurality of the encoders provided corresponding to the plurality of printing units.

In the above, it is possible to provide a means for permitting the driving of the printing element even during acceleration after the start of the relative scanning and / or during deceleration for ending the relative scanning.

[0011] The printing means may use a plurality of printing means corresponding to printing agents having different color tones.

The printing means includes, as the printing element, an ejection port for ejecting ink as a printing agent applied to the print medium, and a means for generating energy used for ejecting the ink. It can be.

Here, the means for generating energy used for discharging the ink may include an electrothermal converter for generating thermal energy in response to energization, and further includes an electrothermal converter. The ink can be ejected from the ejection port toward the print medium by utilizing the film boiling generated in the ink by the applied thermal energy.

Further, an image forming system according to the present invention includes an image forming apparatus according to any one of the above-described embodiments, and means for supplying image information to the image forming apparatus.

Here, the image information supply means may include reading means for reading a document image, and means for processing the read image information and supplying the processed image information to the image forming apparatus.

In this specification, "print" and "recording" refer not only to forming significant information such as characters and figures, but also to widely form (print) images, patterns, and patterns on a medium. If you do. Also,
"Print media" is not limited to paper used in general recording devices, but also widely accepts ink, processing agents, and other printing agents ejected by the head, such as cloth, plastic films, and metal plates. Shall also say.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

In the following, some embodiments in which the present invention is applied to an image forming system in the form of a copying apparatus integrally provided with a reading section for a document image will be described, but the present invention is not limited to these embodiments. . For example, as a form of the image forming system, a reading sensor mounted on a carriage as a scanning member, which may be juxtaposed or replaced with a print head, or a form of the image forming apparatus may be provided separately from a reading unit or It may be provided independently and execute a printing operation by receiving image data from a reading unit, a computer or other image information supply means.

(First Example) (1) Image Forming System FIG. 1 is a schematic diagram showing an example of the configuration of a reading unit serving as a supply source of image information to an image forming apparatus, and FIG. 1 is a block diagram illustrating a configuration example of a signal processing system of an image forming system in a copying apparatus mode including an apparatus, and a flow of image processing in the copying apparatus will be described with reference to these drawings.

A reading area for setting an original and an area of a white plate 53 used for shading correction are provided on the original table glass 52. Information on the original placed on the platen glass 52 and the white plate 53 is transmitted to an original illumination lamp 54.
Is turned on to irradiate the light to the original or the white plate 53 via the original platen glass 52, and the reflected light passes through a rod lens array or a converging optical fiber array (such as a selfoc lens made by Nippon Sheet Glass) 55. The light passes through a CCD (image reading sensor) 1 and is read by being converted from an optical signal into an electric signal.

In this embodiment, the CCD 1, the rod lens array 55, and the document illumination lamp 54 are arranged on the main scanning carriage 51, and the main scanning carriage scans a reading area to read an image.

The image signal converted into an electric signal by the CCD 1 is input to an analog signal processing circuit 2 at the next stage.
The analog signal processing circuit 2 converts the input signal into the signal A of the next stage.
The signal is amplified so as to conform to the input dynamic range of the / D converter 3. In general, the analog signal processing circuit 2 uses a circuit using a plurality of OP amplifiers or the like or a circuit using a dedicated IC, and is configured so that an arbitrary amplification factor can be selected.

The A / D converter 3 converts the input analog image signal into a digital image signal. The image signal converted into the digital signal is output from the shading correction circuit 4 to the light amount distribution unevenness of the
1 corrects the variation of the image signal due to the sensitivity difference of each read pixel. The image signal subjected to the shading correction is input to a color filter (red (R), green (G), blue (B)) of the CCD 1 by the input masking circuit 5.
Is converted to the standard color space of the color.

The image signal converted to the color standard color space is scaled by a scaling circuit 6 to a target image size. The scaled image signal is converted to R,
The G and B luminance signals are converted into C, M and Y density signals. The image signals converted into the C, M, and Y density signals are output by an output masking / UCR circuit 8 from a standard color space of a color to a color space in consideration of the characteristics of the printer, that is, C, M, and Y.
The M and Y signals are converted into C, M, Y and K signals.

The C, M, Y, and K image signals are converted into target densities by a γ conversion circuit 9, and further converted by a binarization processing circuit 10 from an 8-bit multilevel signal to a binary signal. After that, the image is formed on a print medium by the printer 11 which is a main part of the image forming apparatus.

(2) Printing Means and Reading Means Next, the printing means used in the printer 11 and the operation of the image reading means prior to printing will be described. The printer 11 used in this example is
An on-demand type ink jet print head is used in which a plurality of ejection ports are linearly arranged and an image is formed by ejecting ink from the ejection ports in accordance with an image to be printed.

FIG. 3 shows an example of the configuration of an ink jet print head. As shown in the drawing, the head 22 of the present example has a discharge unit 202 in which 512 discharge ports are linearly arranged from a first nozzle at one end to a 512th nozzle at the other end, for example. The line is printed in a direction different from the direction of. That is, the head 22 or a carriage as a mounting member thereof is moved (main scanning) in the direction of arrow A in FIG. 3 by drive control means (not shown), and when one main scanning is completed, the print medium is moved in a direction different from the direction A. And the scanning is performed alternately, so that the band width is sequentially applied to the print medium (corresponding to the ejection port arrangement range).
A minute line print is performed.

The print resolution of the ink jet printer is determined by the arrangement pitch of the nozzles of the print head and the movement accuracy in the direction of arrow A in FIG. For example, if the arrangement pitch of the ejection openings of the print head is 0.0635 mm, a printer having a resolution of 400 dpi can be basically constructed. Here, 0.0635 m in the direction of arrow A
A movement accuracy of m pitches is required. As described above, the number of nozzles of the print head of this inkjet printer is 51.
If it is two, the print width of one band is 0.06
35 × 512 = 32.512 mm. Therefore, in order to obtain the above resolution also in the sub-scanning direction, after one band printing by one main scanning is completed, the print medium is moved in the direction of arrow B perpendicular to arrow A by a paper feed mechanism (not shown). The next band print can be performed by feeding the paper by 512 mm. The ink jet printer can perform a desired amount of printing by repeating the above scanning and print control.

An appropriate reading method of an image reading apparatus (hereinafter, referred to as a scanner) for such an ink jet printer is a band reading method corresponding to band printing of the printer. That is, as shown in FIG. 4, from the first pixel at one end to the 512th pixel at the other end,
By using a scanner having a reading unit 212 having a 512-pixel image reading sensor 1 having linearly arranged reading elements, a desired read image can be read in accordance with the configuration of the print head. In this example, similarly to the ejection unit 202 of FIG. 3, the pixel pitch is set to 0.0635 mm, and the movement pitch in the direction of arrow A is set to 0.0635 mm.
Scanner is configured.

(3) Prerequisite technology for print head and print operation of this embodiment Here, prior to the description of the main part of the present embodiment, the prerequisite technology will be described.

First, the positional relationship between ink dots ejected on a print medium will be described with reference to FIG. Here, for simplification of description, it is assumed that the head has four ink ejection ports as shown in FIG.

In the process of moving the head in the direction indicated by the arrow, the discharge ports discharge ink in the order of. As a result, a delay occurs in the drive time of 〜, and the carriage also moves during the delay time. As a result, as shown in FIG. Formed on print media.

If the simultaneous ejection is performed from the ejection ports 1 to 3, the ink dots are not inclined with respect to the moving direction and are vertical, but in an actual head, a large number (512 in this example) of ejections for each color. Since there is an outlet, when all of the elements that generate energy used for ink ejection are simultaneously driven to perform simultaneous ejection, a large current flows instantaneously. For this reason, the energy generation element group in the head is divided into several blocks, time-division driving is performed in block units, and the current flowing through the head is prevented from being instantaneously concentrated by shifting the ink ejection timing between the blocks. I have to.

For the sake of simplicity, it is assumed that the ejection is performed in a time-division manner from the four ejection openings. As shown in FIG. 5B, the print result is inclined with respect to the moving direction of the carriage. Since a step occurs in an image portion that should be a straight line, in an actual apparatus, FIG.
As shown in the figure, the arrangement direction of the ejection ports in the head is inclined with respect to the moving direction of the head in consideration of the speed of the head moving in the direction of the arrow and the delay in driving the energy generating element corresponding to each ejection port. It corresponds by that.

That is, as shown in FIG. 6 (A), by mounting the head with the ejection port arrangement direction inclined, the ink dots are aligned in the direction perpendicular to the moving direction of the head as shown in FIG. 6 (B). It is configured to obtain a printed result.

Next, referring to FIG. 7, the four C, M, Y, and K
A problem that occurs when the moving speed of the carriage 60 is reduced at the position A in the process of performing printing by ejecting ink while moving the carriage 60 by independently mounting the color heads on the carriage 60 will be described. .

Since the head for discharging the C color ink is moving at a constant speed until the carriage 60 reaches the position A, as shown in the print result for the C color,
Print vertical lines at equal intervals. However, if the moving speed of the carriage 60 becomes slow just before the position A for some reason, a vertical line is printed before the position shown by the broken line, which is supposed to print a vertical line. Since the head that ejects the K color ink is moving at a constant speed until the carriage 60 reaches the position A, vertical lines are printed at equal intervals as shown in the print result for the K color. . However, if the moving speed of the carriage 60 becomes slow just before the position A for some reason, a vertical line is printed before the position indicated by the broken line, which is supposed to print a vertical line.

In the actual printing operation, since the print result of C and the print result of K are combined on the print medium, the carriage 60 moves at a constant speed as shown by the print results of C and K. As long as there is, the C and K inks overlap. However, as the moving speed of the carriage 60 becomes slow, as shown in the print results of C and K, the inks of C and K do not overlap at the positions of the shifts b and c shown by arrows, and Results different from the print data shown in (1) (the original print example). In this manner, not only when the moving speed of the carriage 60 decreases at the position A, but also at
If the moving speed becomes higher than the target speed, the vertical line is printed before the position indicated by the broken line where the vertical line should be printed. Is apparently shifted. Although not shown in FIG. 7, M and Y
Obviously, the printing result by the head that discharges the color ink is also affected by the movement speed fluctuation of the carriage 60 at the position A.

That is, in a control system that only moves the carriage 60, if the movement speed of the carriage 60 fluctuates in the print range, the ink ejection position is shifted, and conventionally, as shown in FIG. By using a combination of the scale 61 and the optical encoder 62 (hereinafter, this optical encoder is simply referred to as an encoder unless otherwise specified), when the moving speed of the carriage 60 fluctuates, the influence is affected. A technique to avoid this was used. For example, an encoder 62 is mounted at the position of the C color head of the carriage 60, the position information written in advance on the scale 61 is read by the encoder 62, and the ink ejection timing of the head is controlled based on the read position information. Thus, even if the moving speed of the carriage 60 fluctuates with respect to the target speed, the ink is discharged to the target position on the print medium 63 without being affected by the fluctuation.

FIG. 9 shows the structure of the scale 60. The scale 60 is formed by drawing a group of black lines in parallel on a transparent tape, and the lines are arranged at a constant interval α. The encoder 62 moves on the scale 61 and outputs a signal every time it crosses the black line. That is, the encoder 62 generates a signal every time the carriage 60 moves at the interval α of black lines shown in the scale 61 (0.0635 mm in this example).
By ejecting the ink of the head with reference to the timing of the signal output from the second unit 2, it is possible to eject the ink to a target position even if the speed of the carriage 60 fluctuates.

Next, a description will be given of inconveniences that occur in the above-described control using one encoder 62.

FIG. 10 shows an example in which the carriage 60 starts moving from the stopped position in the direction of the arrow to perform printing. FIG. 7A shows the print result of C color and the print result of K color when printing is started immediately after the movement of the carriage 60 starts. When the carriage 60 starts moving, the carriage 60 gradually moves. Although the moving speed is increased (speed fluctuation in a broad sense), it is conceivable that the discharge positions of the C and K inks do not deviate because the encoder 62 is used. However, in practice, the formation positions of the C and K ink dots are shifted. This is for the following reason.

FIG. 10B shows the result of ink ejection when the head C reaches the position d immediately after the carriage 60 starts moving in the direction of the arrow. At the time when the head C is at the position d, the moving speed of the carriage 60 is lower than the target speed, so that the ejection port arrangement direction is inclined with respect to the moving direction of the head so that an optimal image can be obtained at the target speed. The influence of the method of FIG. 6 causes a line that should be perpendicular to the moving direction to be printed obliquely as shown in FIG.

FIG. 10C shows the ink ejection result when the carriage 60 starts moving in the direction of the arrow and the head K reaches the position d. Head K
Is at the position d, the moving speed of the carriage 60 is closer to the target speed than in the case shown in FIG. 6B, so that the effect of the method of FIG. 6 is reduced. As a result, the influence of a line that should be perpendicular to the moving direction printed obliquely is reduced.

FIG. 10D shows a state where the print results of the C ink and the K ink at the position d are combined. It can be seen that the print dots of the C ink and the K ink are formed at the same position at the position, but the print positions of the C ink and the K ink are shifted at the position. That is, compared to the method of ejecting ink without using the encoder 62, the case where the ink ejection position control is performed using one encoder 62 is more effective.
The influence of the speed fluctuation on the carriage 60 is small, but the influence cannot be completely eliminated. For this reason, even when the ink ejection position is controlled using the encoder 62, it is necessary to adopt a device configuration that minimizes the speed fluctuation in the carriage 60.

That is, as shown in FIG. 11, when an image is formed on the print medium 63, it is necessary to move the carriage 60 at a constant speed while the carriage 60 moves from the position e to the position f. It is becoming. Also,
To move the carriage 60, a motor is generally used as a drive source. However, a running distance is required to reach a certain target speed from the start of the movement of the carriage 60. After one-line printing, the carriage 6
When stopping at 0, instantaneous stopping cannot be performed due to the inertia of the carriage 60 or the head, and a stopping distance is required.

Therefore, the carriage 6 as shown in FIG.
Therefore, a speed control of 0 is required, and as shown in FIG. 12, a space is required on the side of the existing space of the print medium 63 for performing control in accordance with the approach distance and the stop distance of the carriage 60.

Further, since only a single encoder 62 is provided for the carriage 60, for example, as shown in FIG. In order to match the print result of Y, M, and K with the print result of C in the moving direction, the distance to each of the Y, M, and K heads based on the C head is determined by the interval α shown on the scale 61 in FIG. It was also necessary to make it a positive multiple of.

(4) Main Parts of First Embodiment Next, the contents of the main parts of the first embodiment of the present invention will be described.

FIG. 14 shows a basic configuration example of this embodiment. In this example, C,
A head for ejecting each color ink of M, Y, and K is mounted, a dedicated encoder 62 is mounted for each head, and a scale 61 dedicated to each head is used. It is configured to obtain. Further, by using the head drive block shown in FIG. 17 for each color, a configuration is adopted in which even if the movement of the carriage 60 fluctuates, the ink ejection position is not affected.

The structure and operation of the head drive block shown in FIG. 17 will be described with reference to FIGS. 18 and 19.

The clock generator 64 is for generating a reference clock for measuring the interval between the signals of the encoder 62. The output of the clock generator 64 is input to the counter 65. The counter 65 includes the clock generator 6
The number of clocks supplied from 4 is counted, and the count value is cleared to zero when the encoder signal rises. The output of the counter 65 is applied to a flip-flop 66 and a ROM 67, respectively.

The flip-flop 66 stores the value when the encoder signal rises. That is, the interval between encoder signals is measured by storing the number of clocks of the clock generation unit 64 corresponding to the section from the rise of the encoder signal to the rise of the next encoder signal.

The ROM 67 previously stores timing information of drive signals for the energy generating elements corresponding to intervals of various encoder signals. ROM67
The output signal of the flip-flop 66 (interval information of the encoder) signal line is connected to the upper address, and the output of the counter 65 (which position in one section (A to C) of the encoder signal corresponds) is connected to the lower address. Information) The signal line is connected.

From the ROM 67, drive timing signals Q1 to Q4 for the energy generating elements corresponding to the discharge ports are output and applied to the AND gate 68. In addition, each A
Each color print data is supplied to the other input terminal of the ND gate 68, and only when there is print data, an energy generating element corresponding to each ejection port (hereinafter, an ejection port and an energy generating element corresponding to the ejection port) (A print element containing the same is also referred to as a “nozzle”). FIG.
7 is shown.

The carriage 6 will be described with reference to FIGS.
An output example of the nozzle drive signal read from the ROM 67 when the moving speed of 0 is different will be described.

The example of the driving signal shown in FIG.
0 is a state in which it is moving at a predetermined target speed.
The output signal of the encoder 62 is output every time t, and the drive signal of the energy generating element corresponding to the time t is stored in the ROM 67.
More output. At this time, if all the print data satisfy the conditions for ejecting ink, the ejected ink has print dots arranged in a direction perpendicular to the moving direction of the carriage 60 as shown in FIG.

On the other hand, the driving signal example shown in FIG. 21 is a state where the carriage 60 is moving at half the target speed. The output signal of the encoder 62 is time 2t
The drive signal of the nozzle corresponding to time 2t is output from the ROM 67 every time. That is, assuming that the time from the rise of the nozzle drive signal shown in FIG. 20 to the rise of the nozzle drive signal is Z, the time from the rise of the nozzle drive signal to the rise of the nozzle drive signal shown in FIG. Become.

As a result, even if the time required for the carriage 60 to move a predetermined distance is reduced by half, the speed is doubled, and the speed of movement of the carriage 60 is increased by doubling the ejection interval of the ink ejected from the nozzles. Can cancel the influence on the ejection position of the ink, and it is possible to prevent the displacement of the formed dots by each color ink. In addition, in order to perform registration adjustment of the formed dots using the respective color inks in the moving direction of the carriage 60, it is possible to perform adjustment to match the print ejection timing information on the scale 61 dedicated to each color of C, M, Y, and K. The conditions for strictly controlling the dimensional accuracy of the carriage 60 and the head, or the arrangement or assembly accuracy are alleviated.

As a result, as shown in FIG. 15, the carriage 6 is moved so that the C head of the carriage 60 is positioned at the leading end of the print start position in the main scanning direction of the print medium 63.
0 is stopped, the carriage 60 is started to move from the leading end of the print start position, and in the process of accelerating to the target speed, the K head of the carriage 60 is stopped at the print end position of the print medium 63. Even in the process of reducing the speed of the carriage 60 from the target speed, it is possible to form high-quality images without color shift.

That is, as shown in FIG. 16, even if the speed control of the carriage 60 is performed with the acceleration / deceleration period superimposed on the print range, the desired print result can be obtained.

As described above, according to the present embodiment, the scale is prepared for each color head, the scale is read for each color head, and the ink ejection timing is controlled independently for each color. 60 is raised from the stop state to the target speed, the approach distance for keeping the speed constant, and the moving speed kept constant until all the print heads relatively move out of the printing range, and then the carriage speed is reduced. The distance to stop is not required. In addition, since the time required to move the carriage for the distance required for the rise and fall of the carriage is not required, the time required for printing can be reduced, and the print amount per unit time can be increased. That is, it is possible to configure the apparatus with a width substantially adding the print range and the dimension of the carriage 60, which can contribute to miniaturization of the apparatus and improvement of the printing speed.

It should be noted that the information for determining the drive timing of the energy generating element may be updated in accordance with the adjustment in consideration of the replacement of the head and the variation in the mounting accuracy of each device. May be a rewritable device. In addition, in order to facilitate such adjustment, a predetermined test pattern or the like may be formed, read by the image reading means as described above, and the information may be updated according to the result. it can.

In the above description, the image forming apparatus using the heads for ejecting the four color inks of C, M, Y, and K has been described. However, the ink colors used for the heads are not limited thereto. Instead, a desired number of colors (including densities) can be used. For example, the same effect can be obtained when all the four heads are prepared to eject K color ink, and a configuration in which two or more shades of the same color ink are prepared,
For example, the technique described in the present embodiment is similarly applied to a configuration in which multi-level color printing is performed using at least some of the colors C, M, Y, and K using two types of dark and light inks. It is possible to apply.

The print head mounted on the carriage 60 or the ink tank serving as an ink supply source for the head may be formed as a cartridge in which the two are completely integrated, and when the ink remaining in the ink tank is exhausted. For example, the cartridges may be replaced with each other, or both may be detachable so that only the ink tank can be removed and replaced. Alternatively, in addition to integrating them, such as those described above, ink tanks may be provided separately in other portions of the apparatus, and ink may be supplied to the print head by communicating the two with a tube or the like. Good.

(Second Example) FIG. 22 shows a configuration example of the second embodiment of the present invention.

In the present embodiment, C and C are used as in the first embodiment.
An encoder 62 is provided for each of the M, Y, and K heads, but the scale 61 is configured to be used in common for each color. That is, the common scale 61 is read by the encoder 62 corresponding to the head of each color, and printing is performed by using the head drive block shown in FIG. 17 prepared for each color based on the read encoder signal. This is an example configured as follows.

In this embodiment also, speed fluctuation (including acceleration / deceleration)
Can be canceled, but since the encoder 62 is used in common for each color, C, M, Y, K
In order to match the print results in the moving direction of the carriage 60, the carriage 60 and the head are adjusted so that the interval between the Y, M, and K heads is a positive multiple of the interval α shown on the scale 61 in FIG. It is preferable to precisely determine the dimensional accuracy and the like. (Third Example) FIG. 23 shows a configuration example of a third embodiment of the present invention.

In this embodiment, the head and the head for K color are integrated with each other for the three colors C, M, and Y, and the scale and the encoder 62 are separately used for these two heads. It is configured as follows. That is, in this example, the three-color (C, M, Y) integrated head has the C ink ejection unit, the M ink ejection unit, and the Y ink ejection unit on the same line perpendicular to the moving direction of the carriage 60. The printing is performed by using a head drive block shown in FIG. 17 prepared for each color based on a signal read by an encoder 62 attached to the head. Similarly, the encoder 62 attached to the K head
The K-color printing is performed by using a head drive block shown in FIG. 17 prepared for the K-head based on the signal read by the printer.

Even with such a configuration, the same effect as in the first example can be obtained.

(Fourth Example) FIG. 24 shows a configuration example of the fourth embodiment of the present invention.

In this embodiment, the discharge unit for C, M, Y and K is provided in the integrated head, and the scale and the encoder 62 are separately used for the discharge unit of each color. The operation of this example is the same as that of the first example, and similar effects can be obtained.

(Fifth Example) In still another embodiment of the present invention, a magnetic tape used for an audio tape or a video tape is used as the scale 61. The magnetized information is written on the magnetic tape at regular intervals in the same manner as in the scale configuration example shown in FIG. The information written on the magnetic tape is read by an encoder 62 capable of reading magnetism using a Hall element or the like, and based on the read result, printed in the same manner as in the above examples. Can be configured to perform the following. That is, as described above, the scale and the encoder applied to the present invention are not limited to the optical type, and appropriate ones can be used.

(Configuration of Control System) FIG. 25 shows an example of the configuration of a control system of an image forming apparatus to which the above embodiments can be applied. In the figure, 500 and 501 are a print control unit and a head unit, respectively. Reference numeral 400 denotes an interface for transmitting and receiving print data and the like to and from an image reading unit and other host devices; 401, an MPU serving as a main control unit of the device; 402, a program corresponding to a control procedure executed by the MPU; A dynamic RAM (DRA) 403 for storing various data (a control signal for a printing operation, print data to be supplied to the print head 201, and the like).
M).

A gate array 404 controls supply of print data to the print head, and also controls data transfer between the interface 400, the MPU 401, and the DRAM 403. Reference numeral 405 denotes a paper feed motor serving as a drive source for transporting paper in the sub-scanning direction. Reference numerals 407 and 408 denote motor drivers for driving the carriage motor 8 and the paper feed motor 405, respectively. Reference numeral 409 denotes a head driver for driving the print head 1, and a control circuit as shown in FIG. 17 can be provided here.

(Others) The present invention is an apparatus for performing printing by arranging a plurality of print head units having print elements in parallel and scanning relative to a print medium in a direction different from the arrangement direction. If it is, it is not limited to the inkjet printing method as described above, a thermal transfer method,
It is needless to say that the present invention can be applied to an apparatus employing a wire dot system or other various systems.

There are various types of ink jet recording (printing) apparatuses. Means for generating thermal energy (for example, an electrothermal converter, a laser beam, or the like) is used as energy used for ink ejection. The present invention provides an excellent effect in a recording head and a recording apparatus of a type in which a change in the state of ink is caused by the thermal energy. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal on a one-to-one basis.
This is effective because air bubbles inside can be formed. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

The configuration of the recording head is not limited to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned respective specifications. U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44,558 which disclose a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

Further, even with respect to a full-line type recording head having a length corresponding to the maximum width of the recording medium that can be recorded by the recording apparatus, a plurality of recording heads are juxtaposed in the relative transport direction of the printing medium. In this case, the present invention can be effectively applied to cancel the fluctuation of the transport speed.
Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head.

Further, in the serial type apparatus as described above, a recording head fixed to the apparatus main body, or an electric connection with the apparatus main body or supply of ink from the apparatus main body by being mounted on the apparatus main body. The present invention is also effective when a replaceable chip-type recording head which enables the recording or a cartridge-type recording head in which an ink tank is provided integrally with the recording head itself is used.

It is preferable to add a recording head ejection recovery unit, a preliminary auxiliary unit, and the like as a configuration of a recording apparatus applicable to the present invention, since the effects of the present invention can be further stabilized. If you list these specifically,
Pre-heating means for heating using a capping means, a cleaning means, a pressure or suction means, an electrothermal converter or another heating element or a combination thereof for the recording head, and recording Pre-discharge means for performing another discharge can be given.

Further, as described above, a plurality of recording heads may be provided corresponding to a plurality of inks having different recording colors and densities. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, but may be any of integrally forming a printing head or a combination of a plurality of printing heads. The present invention is also very effective for an apparatus provided with at least one of the recording modes of full color by color mixture.

In addition, in the embodiment of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or lower and which softens or liquefies at room temperature may be used. In general, the ink jet method generally controls the temperature of the ink itself within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Sometimes, the ink may be in a liquid state. In addition, in order to positively prevent temperature rise due to thermal energy by using it as energy for changing the state of the ink from a solid state to a liquid state, or to prevent evaporation of the ink, the ink is solidified in a standing state and heated. May be used. In any case, the application of heat energy causes the ink to be liquefied by the application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start solidifying when it reaches the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used. In such a case, the ink
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent Publication No. 1260, it is also possible to adopt a form in which the sheet is opposed to the electrothermal converter in a state where it is held as a liquid or solid substance in the concave portion or through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, the form of the ink jet recording apparatus applicable to the present invention is not limited to those used as image output terminals of information processing equipment such as computers.
A copying machine combined with a reader or the like, or a facsimile machine having a transmission / reception function may be used.

[0086]

As described above, according to the present invention,
In an apparatus in which a plurality of printing means having printing elements are arranged and printing is performed by scanning relative to a printing medium in a direction different from the arrangement direction, the driving timing of the printing elements is independent for each printing means. So that the starting speed from the stop of scanning to the target speed, and the approach distance to keep the speed constant,
The moving speed is kept constant until all the printing means are relatively moved out of the printing range, and thereafter, the distance between the carriage speed reduction and the stop is not required. That is, since the start-up for scanning and the section required for the start-up are shortened, the size of the apparatus can be reduced and the printing speed or throughput can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a configuration of a reading unit serving as a supply source of image information to an image forming apparatus.

FIG. 2 is a block diagram illustrating a configuration example of a signal processing system of an image forming system of a copying apparatus including a reading unit and an image forming apparatus.

FIG. 3 is an explanatory diagram for describing a configuration example of an inkjet print head and a printing operation.

FIG. 4 is an explanatory diagram illustrating a configuration example of an image reading sensor and a reading operation.

FIGS. 5A and 5B are explanatory diagrams for explaining a conventional arrangement of ink ejection ports and a state of forming print dots by the arrangement.

FIGS. 6A and 6B are explanatory diagrams for explaining an arrangement of ink ejection ports used in an embodiment of the present invention and a state of forming print dots by the arrangement.

FIG. 7 is an explanatory diagram for describing a print example when a speed fluctuation occurs in a carriage.

FIG. 8 is an explanatory diagram of a print head scanning system as a premise of the present invention.

FIG. 9 is a diagram showing a configuration example of a scale that can be employed in the scanning system of FIG. 8;

FIGS. 10A to 10D are explanatory diagrams for explaining a print example in a case where a printing operation is performed at the time of starting up a carriage using the scanning system of FIG. 8;

FIG. 11 is an explanatory diagram for explaining a print range when the scanning system of FIG. 8 is used.

FIG. 12 is an explanatory diagram for explaining a carriage movement range when the scanning system of FIG. 8 is used.

FIG. 13 is a diagram showing a relationship between a carriage position and a moving speed when the scanning system of FIG. 8 is used.

FIG. 14 is an explanatory diagram of a print head scanning system according to an embodiment of the present invention.

FIG. 15 is an explanatory diagram for describing a print range and a carriage movement range when the scanning system of FIG. 14 is used.

16 is a diagram showing a relationship between a carriage position and a moving speed when the scanning system of FIG. 14 is used.

17 is a block circuit diagram showing a configuration example of a print head drive block corresponding to the scanning system of FIG.

FIG. 18 is a timing chart for explaining the operation of the circuit in FIG. 17;

FIG. 19 is a timing chart showing an example of a nozzle drive signal generated by the circuit of FIG.

FIG. 20 is a timing chart illustrating an output example of a nozzle drive signal according to a change in carriage moving speed.

FIG. 21 is a timing chart showing an output example of a nozzle drive signal according to a carriage movement speed variation.

FIG. 22 is an explanatory diagram of a print head scanning system according to a second embodiment of the present invention.

FIG. 23 is an explanatory diagram of a print head scanning system according to a third embodiment of the present invention.

FIG. 24 is an explanatory diagram of a print head scanning system according to a fourth embodiment of the present invention.

FIG. 25 is a block diagram illustrating a configuration example of a control system of an image forming apparatus to which each embodiment of the present invention can be applied.

[Explanation of symbols]

 1 CCD 11 Printer 22 Print Head 60 Carriage 61 Scale 62 Encoder 63 Print Medium 64 Clock Generation Unit 65 Counter 66 Flip-Flop 67 ROM 68 AND Gate 202 Ejection Unit

Claims (10)

[Claims] An apparatus for forming an image by using a plurality of printing means having printing elements and scanning relative to a print medium in a direction different from a direction in which the plurality of printing means are arranged, Means for detecting the relative position of each of the plurality of printing means in the scanning direction; and independently controlling the drive timing of the printing element for each of the plurality of printing means based on the detected information. And an image forming apparatus. 2. The detecting means has a scale extending in the scanning direction and having information formed at predetermined intervals, and an encoder which is relatively scanned with the printing means and detects formed information on the scale. The image forming apparatus according to claim 1, wherein a plurality of sets of the scale and the encoder are provided corresponding to the plurality of printing units. 3. The encoder according to claim 1, wherein the detector is a single scale extending in the scanning direction and having information formed at predetermined intervals, and an encoder which is relatively scanned together with the printing means to detect formation information on the scale. The image forming apparatus according to claim 1, further comprising a plurality of encoders provided corresponding to the plurality of printing units. 4. During acceleration after the start of said relative scanning and / or
4. The image forming apparatus according to claim 1, further comprising a unit that permits the driving of the print element even during deceleration for ending the relative scanning. 5. The image forming apparatus according to claim 1, wherein the plurality of printing units correspond to printing agents having different color tones. 6. The printing means includes, as the printing element, an ejection port for ejecting ink as a printing agent applied to the print medium, and means for generating energy used for ejecting the ink. The image forming apparatus according to any one of claims 1 to 5, further comprising: 7. The device according to claim 6, wherein the means for generating energy used for discharging the ink includes an electrothermal converter for generating thermal energy in response to energization.
An image forming apparatus according to claim 1. 8. The method according to claim 7, wherein the ink is ejected from the ejection port toward a print medium by utilizing film boiling generated in the ink by thermal energy applied from the electrothermal converter. Image forming apparatus. 9. An image forming system comprising: the image forming apparatus according to claim 1; and means for supplying image information to the image forming apparatus. 10. The image forming apparatus according to claim 9, wherein the image information supply unit includes a reading unit that reads a document image, and a unit that processes the read image information and supplies the processed image information to the image forming apparatus. Image forming system.